This invention relates general to the field of actuating hydraulically controllable downhole tools and, in particular to, a remotely operated service tool having a self-contained hydraulic system for actuating hydraulically controllable downhole tools disposed within a wellbore.
Without limiting the scope of the invention, its background is described in connection with setting a packer assembly in a wellbore that traverses a hydrocarbon formation, as an example.
Heretofore in this field, during the treatment and preparation of the wellbore for production, a packer assembly and sand control screen along with a service tool are run into the wellbore on a work string. The setting of the packer assembly against the casing is typically accomplished by manipulating the service tool. The success of such operations is dependent upon the ability to reciprocate the service tool vertically or to rotate it relative to the packer assembly. It has been found, however, that rotational displacement of the service tool in deviated wells is difficult to perform reliably because of frictional binding between the work string and the casing. Accordingly, vertical reciprocal movements have been preferred for setting and releasing packer assemblies in such instances.
During run-in, the packer assembly is mechanically locked in the unset condition by shear pins and anti-preset lugs that support the weight of the packer assembly along with the hang weight of other components such as a swivel shear sub, blank pipe, a sand control screen, a polished nipple, a tail screen, and a packer assembly. The shear pins and anti-preset lugs can safely support the combined weight of the downhole equipment. The shear pins are rated to yield to a preset shearing force to separate and release the service tool after the packer assembly has been set. It has been found, however, that in deviated or otherwise obstructed wellbores, shear pins designed to shear in response to vertical reciprocation may be damaged and the packer assembly may sometimes be inadvertently preset in response to frictional loading between the packer assembly and the wellbore in tight spots.
It has also been found that when operating in slanted or deviated wellbores, it is sometimes difficult to transmit sufficient force downhole from the surface to set mechanically actuated packer assemblies. The frictional engagement between the wellbore and the work string interferes with the transmission of the necessary mechanical force to set the packer assembly.
To overcome these difficulties, pressure may be applied to the fluid column within the work string to transmit the required packer assembly setting force. For example, the packer assembly may be set by dropping a ball through the work string into the service tool. Pressurized fluid is then pumped down the work string to shear the shear pins, thereby setting the packer assembly. During gravel packing or frac packing operations, it is desirable to remove the ball from the service tool. It has been found, however, that in slanted or deviated wellbores or in tapered work strings it is difficult to reverse the ball out of the work string. In addition, it has been found that the ball, in certain installation, may damage downhole equipment when it is run-in the service tools.
Therefore a need has arisen for an improved service tool for running and setting a packer assembly in a wellbore. A need has also arisen for an improved service tool for setting a packer assembly without the need for translational or rotational movement of the service tool with respect to the packer assembly and without the need for running a ball into the service tool. A need has further arisen for such a service tool that can set a packer assembly in a deviated or slanted wellbore.
The present invention disclosed herein comprises a service tool for hydraulically actuating a downhole device from a remote location. The service tool utilizes hydraulic pressure for actuating the downhole device without the need for translational or rotational movement of the service tool and without the need for running a ball into the service tool. The service tool of the present invention may be used in any wellbore including a deviated or slanted wellbore.
The service tool of the present invention comprises a downhole hydraulic fluid source, a hydraulic fluid passageway that provides a communication path between the downhole hydraulic fluid source and the hydraulically controllable device, a valve disposed within the hydraulic fluid passageway and a downhole electronics package. The downhole electronics package receives a signal from a surface installation to operate the valve from the closed position to the open position, thereby transmitting hydraulic pressure from the downhole hydraulic fluid source to the hydraulically controllable device and actuating the hydraulically controllable device.
The hydraulic fluid source includes a housing and a sleeve that define a hydraulic fluid chamber therebetween having hydraulic fluid contained therein. The sleeve is slidably disposed about the housing and has first and second positions relative to the housing. The sleeve is operated from the first position to the second position, responsive to hydrostatic pressure, once the valve is operated from the closed position to the open position. The sleeve and the housing also define an atmospheric air chamber therebetween having air contained therein.
The downhole electronics package includes a transducer that receives the signal from a surface installation. The transducer may be selected from a variety of transducers that are suitable for downhole reception of a signal including, but not limited to, an acoustic transducer, a pressure pulse transducer, an electromagnetic transducer and the like. The transducer receives the signal and relays the signal to the controller of the valve. The downhole electronics package also includes a battery pack to provide a source of electrical power.
The method for actuating a downhole device of the present invention involves sending a signal to a downhole electronics package, transmitting hydraulic pressure from a downhole hydraulic source to the downhole device in response to the signal and actuating the downhole device in response to the hydraulic pressure. The method may also include operating a valve to establish a communication path between the downhole hydraulic source and the downhole device and utilizing hydrostatic pressure to transmit the hydraulic fluid from the downhole hydraulic source to the downhole device.
In the method of the present invention, the signal may be sent to a downhole electronics package from a surface installation. The signal may be an acoustic signal, a pressure pulse signal, an electromagnetic signal or other suitable signal the may be received downhole.
The actuation of the downhole device may further include the setting a downhole device such as a packer assembly, or the manipulating a downhole device such as a sliding sleeve, a fluid control device or a well control device. Additionally, the actuation of the downhole device may be achieved by axially shifting a component of the downhole device or rotatably operating a component of the downhole device.